If your staying in the Mystic area. a day trip to the Newport RI & the Mansions is worth a day trip. Lots of Pubs and good eats in upscale Newport.
If you can get reservations at
https://www.campgroundreviews.com/regions/rhode-island/narragansett/fishermens-state-park-and-campground-4381#review_462273 you will be down the road from the Narragansett beaches, ferry to scenic Block Island. Narrangansett has lots of local charm. Also you are still in range of day trips to everything mentioned on this thread as the campground is central to most everything.
Mike
